1. Field of the Invention
The present invention relates to an electrophographic image forming apparatus which makes an electrostatic latent image visible on an image carrier using a development device and enables printed output of a visible image on a recording medium.
2. Description of the Related Art
An image forming apparatus compatible with a color image has recently become common. Some pieces of image forming apparatus compatible with a color image have four development devices assigned to respective color components of YMCK, and a rotary (revolving body) unit having the development devices provided around a rotary shaft. In the image forming apparatus having such a configuration, the respective development devices integrally rotate in association with rotation of the rotary unit, whereby the development devices sequentially move to a development position where the development device faces a photosensitive drum which serves as an image carrier. Consequently, after having made an electrostatic latent image on the photosensitive drum visible as a toner image, the development device located at the development position transfers the toner image to an intermediate transfer body, or the like. These operations are sequentially repeated such that the toner images formed by the respective development devices are superposed on the other on the intermediate transfer body or the like, so that a transfer image corresponding to the color image is formed on the intermediate transfer body or the like.
In the electrophotographic image forming apparatus, the electrostatic latent image on the photosensitive drum is generally made visible as a toner image. Accordingly, the concentration of toner and the amount of remaining toner greatly affect the image quality of a formed image. In view of this, an image forming apparatus, which has a rotary unit and is compatible with a color image, has hitherto been proposed to detect and monitor, by means of a custom-designed sensor, or the like, the concentration of toner or the amount of remaining toner; to read information inherent to the development device(toner attribute information, operation history information, and the like) from a noncontact information medium belonging to the development device; and to perform control operation on the basis of the read information, to thereby maintain the image quality of the formed image well.
However, in relation to an image forming apparatus having a related-art rotary unit, the apparatus performs detection of a state or acquisition of information pertaining to a single matter; for instance, only the concentration of toner in a case where the apparatus detects the concentration of toner, or only the amount of remaining toner in a case where the apparatus detects the amount of remaining toner. The result of state detection or acquisition of information is used for maintaining the image quality of a formed image. Consequently, elaborate and flexible response cannot always be realized.
In this regard, detection of a state or acquisition of information can be considered to be performed in relation to a plurality of matters. Detection of a state and acquisition of information requires a stop of rotation of the rotary unit for each object of the detection. Therefore, an increase in the number of matters, which are to be subjected to detection of a state or acquisition of information, may result in a corresponding drop in productivity pertaining to formation of an image.